gesture recognizer: Recognizer rotation gestures.

ui/base/gestures/gesture_sequence.cc

Index: ui/base/gestures/gesture_sequence.cc
diff --git a/ui/base/gestures/gesture_sequence.cc b/ui/base/gestures/gesture_sequence.cc
index 2c3b599e78f8e7771aaaed6ac9084b66a27e6732..1f2a19afbb15b3df8c3fe7208cb8f8af550391b8 100644
--- a/ui/base/gestures/gesture_sequence.cc
+++ b/ui/base/gestures/gesture_sequence.cc
@@ -264,6 +264,12 @@ float BoundingBoxDiagonal(const gfx::Rect& rect) {
   return sqrt(width + height);
 }
 
+float BoundingBoxDiagonalAngle(const gfx::Rect& rect) {
+  float width = rect.width();
+  float height = rect.height();
+  return width == 0.f ? M_PI_2 : atan(height / width);
+}
+
 unsigned int ComputeTouchBitmask(const GesturePoint* points) {
   unsigned int touch_bitmask = 0;
   for (int i = 0; i < GestureSequence::kMaxGesturePoints; ++i) {
@@ -291,6 +297,7 @@ float CalibrateFlingVelocity(float velocity) {
 GestureSequence::GestureSequence(GestureEventHelper* helper)
     : state_(GS_NO_GESTURE),
       flags_(0),
+      bounding_box_diagonal_angle_(0.f),
       pinch_distance_start_(0.f),
       pinch_distance_current_(0.f),
       scroll_type_(ST_FREE),
@@ -474,6 +481,7 @@ GestureSequence::Gestures* GestureSequence::ProcessTouchEventForGesture(
     case GST_PINCH_FIFTH_PRESSED:
       pinch_distance_current_ = BoundingBoxDiagonal(bounding_box_);
       pinch_distance_start_ = pinch_distance_current_;
+      bounding_box_diagonal_angle_ = BoundingBoxDiagonalAngle(bounding_box_);
       break;
   }
 
@@ -508,6 +516,7 @@ GestureSequence::Gestures* GestureSequence::ProcessTouchEventForGesture(
     if (state_ == GS_PINCH) {
       pinch_distance_current_ = BoundingBoxDiagonal(bounding_box_);
       pinch_distance_start_ = pinch_distance_current_;
+      bounding_box_diagonal_angle_ = BoundingBoxDiagonalAngle(bounding_box_);
     }
   }
   return gestures.release();
@@ -752,11 +761,12 @@ void GestureSequence::AppendPinchGestureEnd(const GesturePoint& p1,
 
 void GestureSequence::AppendPinchGestureUpdate(const GesturePoint& point,
                                                float scale,
+                                               float rotation,
                                                Gestures* gestures) {
   // TODO(sad): Compute rotation and include it in delta_y.
   // http://crbug.com/113145
   gestures->push_back(CreateGestureEvent(
-      GestureEventDetails(ui::ET_GESTURE_PINCH_UPDATE, scale, 0),
+      GestureEventDetails(ui::ET_GESTURE_PINCH_UPDATE, scale, rotation),
       bounding_box_.CenterPoint(),
       flags_,
       base::Time::FromDoubleT(point.last_touch_time()),
@@ -932,6 +942,8 @@ bool GestureSequence::PinchStart(const TouchEvent& event,
 
   pinch_distance_current_ = BoundingBoxDiagonal(bounding_box_);
   pinch_distance_start_ = pinch_distance_current_;
+  bounding_box_diagonal_angle_ = BoundingBoxDiagonalAngle(bounding_box_);
+
   AppendPinchGestureBegin(*point1, *point2, gestures);
 
   if (state_ == GS_PENDING_SYNTHETIC_CLICK ||
@@ -968,9 +980,18 @@ bool GestureSequence::PinchUpdate(const TouchEvent& event,
 
   if (abs(distance - pinch_distance_current_) >=
       GestureConfiguration::min_pinch_update_distance_in_pixels()) {
-    AppendPinchGestureUpdate(point,
-        distance / pinch_distance_current_, gestures);
+    float scale = distance / pinch_distance_current_;
+    float angle = bounding_box_diagonal_angle_;
+    // Compute rotation only if the the bounding box remained of roughly the
+    // same size.
+    if (fabs(1.f - scale) < 0.15f)
+      angle = BoundingBoxDiagonalAngle(bounding_box_);
+    else
+      LOG(ERROR) << "Scale: " << scale;
+    AppendPinchGestureUpdate(point, scale, angle - bounding_box_diagonal_angle_,
+        gestures);
     pinch_distance_current_ = distance;
+    bounding_box_diagonal_angle_ = angle;
   } else {
     gfx::Point center = bounding_box_.CenterPoint();
     AppendScrollGestureUpdate(point, center, gestures);